Phosphonic acid salts, their preparation and their use for fireproofing organic fibre material

ABSTRACT

Novel phosphonic acid salts produced from ethane- or methanephosphonic acid, dicyandiamide and/or guanidine and optionally ammonia and corresponding to the formula ##STR1## wherein n, p, q, t and y are each 1 or 2, are particularly suitable for fireproofing organic fibre materials. Synthetic and/or cellulose-containing fibre materials are treated with an aqueous solution of the phosphonic acid salts and are then dried preferably at 60° to 200° C. The applied phosphonic acid salts impair only negligibly the textile-mechanical properties of the treated fibre materials, especially of the cellulose-containing fibre materials dried at 120° to 150° C.

The present invention relates to novel phosphonic acid salts, toprocesses for producing them, and to their use as fireproofing agentsfor organic fibre material, and also to an application process forfireproofing organic fibre materials by use of the novel phosphonic acidsalts, to an aqueous solution containing the novel phosphonic acidsalts, as an agent for carrying out the application process, and to thefibre materials fireproofed by the process according to the invention.

The phosphonic acid salts according to the invention correspond to theformula ##STR2## wherein n, p, q, t and y are each 1 or 2.

When t in the formula (1) is 2, the phosphonic acid salts correspond tothe formula ##STR3## wherein p, q and y are each 1 or 2.

When p and q in the formula (2) differ from one another, that is to say,when p is 1 and q is 2, or when p is 2 and q is 1, the phosphonic acidsalts correspond to the formula ##STR4## wherein y is 1 or 2, butpreferably 1.

Preferred therefore is the phosphonic acid salt of the formula ##STR5##

When on the other hand p and q in the formula (2) have the same meaning,the phosphonic acid salts, if p and q are 2, correspond to the formula##STR6## wherein y is 1 or 2, but preferably 1.

Preferred therefore is the phosphonic acid salt of the formula ##STR7##

When p and q in the formula (2) have the same meaning as each other,with both p and q being 1, the phosphonic acid salts correspond to theformula ##STR8## wherein y is 1 or 2, but preferably 1.

Preferred therefore is the phosphonic acid salt of the formula ##STR9##

When in the formula (1) t is 2, and p and q have the same meaning aseach other, p and q are preferably 1. Thus the phosphonic acid salts ofthe formulae (5) and in particular (6) are preferred to the phosphonicacid salts of the formulae (7) and (8). Of the phosphonic acid salts ofthe formula (1) in which t is 2, the salts of special interest are thoseof the formula (3) and particularly (4), as well as the salts of theformula (5) and especially (6).

When t in the formula (1) is 1, the phosphonic acid salts correspond tothe formula ##STR10## wherein n, p and y are each 1 or 2.

When p in the formula (9) is 2, the phosphonic acid salts correspond tothe formula ##STR11## wherein n and y are each 1 or 2.

In the formula (10), y is preferably 1. Preferred phosphonic acid saltsthus correspond to the formula ##STR12## wherein n is 1 or 2.

When n in the formula (11) is 1, the phosphonic acid salt concernedcorresponds to the formula ##STR13##

When however n in the formula (11) is 2, the phosphonic acid salt inquestion corresponds to the formula ##STR14##

When p in the formula (9) is 1, the phosphonic acid salts correspond tothe formula ##STR15## wherein n and y are each 1 or 2.

In the formula (14), y is preferably 1. Preferred phosphonic acid saltsthus correspond to the formula ##STR16## wherein n is 1 or 2.

When n in the formula (15) is 1, the phosphonic acid salt concernedcorresponds to the formula ##STR17##

When however n in the formula (15) is 2, the phosphonic acid salt inquestion corresponds to the formula ##STR18##

When t in the formula (1) is 1, n is preferably 2 and p is preferably 1.Among the phosphonic acid salts of the formula (1) wherein t is 1, thesalts of the formulae (14), (15), (16) and (17) are preferred to thesalts of the formulae (10), (11), (12) and (13), the salt of the formula(13) and particularly the salt of the formula (17) being of greatestinterest.

The phosphonic acid salts according to the invention are produced, usingmethods known per se, by reaction of the correspondingphosphorus-containing acids with the appropriate nitrogen-containingbases. The process for producing the phosphonic acid salts of theformula (1) comprises reacting in an aqueous medium, optionally atelevated temperature, 1 mol of phosphonic acid of the formula ##STR19##wherein y is 1 or 2, with 1 mol of a nitrogen compound of the formula##STR20## wherein p is 1 or 2, and 1 mol of a nitrogen compound of theformula ##STR21## wherein q is 1 or 2, when t in the formula (1) is 2,or with 1 mol of a nitrogen compound of the formula (19) and optionally1 mol of ammonia when t in the formula (1) is 1, the nitrogen compoundbeing present as free guanidine, or preferably as guanidine carbonate,when p and q in the formulae (19) and (20) are 2, and the reaction beingperformed with the addition of 1 mol of water when p and q are 1, orbeing performed with removal of 1 mol of carbon dioxide when guanidinecarbonate is used.

In the case of the starting compound of the formula (18), this is,depending on the meaning of y, ethane- or preferably methanephosphonicacid, which is described for example in J. Am. Chem. Soc. 75, 3379 ff(1953); and in the case of the starting compounds of the formulae (19)and (20), these are dicyandiamide when p and q are 1, and guanidine whenp and q are 2.

Where dicyandiamide is used, there occurs in the reaction, as alreadymentioned, an addition of water. The reaction with dicyandiamide ispreferably performed at elevated temperature, for example at 60° to 100°C., and preferably between 85° and 95° C. Also higher reactiontemperatures of, for example, 100° to 130° C., are suitable providedthat the reaction with dicyandiamide is carried out under pressure.

In the reactions with guanidine, the salt thereof is preferably used,namely guanidine carbonate, since guanidine salts are more readilyavailable than free guanidine. For practical reasons, only guanidinecarbonate is suitable as salt, because the corresponding weak acid, thatis, carbonic acid, does not participate in the reaction but is removed,under the applied conditions, as carbon dioxide from the reactionmixture, in contrast to the free acids of the guanidine salts of adifferent kind, such as guanidine hydrochloride or guanidine acetate.With the use of guanidine carbonate, there is taken into account withrespect to the molar ratios stated in the foregoing the fact that 2 molsof free guanidine are present per mol of guanidine carbonate. Thereactions with guanidine or with the carbonate thereof are optionallyperformed at elevated temperature, for example at 20° to 100° C.,preferably at 20° to 60° C., and particularly at 40° to 60° C. Whereguanidine carbonate is used, a temperature of 40° to 60° C. isespecially desirable in order to accelerate the evolution of carbondioxide. The removal of carbon dioxide from the reaction mixture can becompleted or accelerated under reduced pressure, suitable temperaturesin this case being between 20° and 40° C.

The reaction with ammonia occurs only when n and t in the formula (1)are both 1. In this case, the ammonia is preferably used in the form ofan aqueous solution. The optional reactions with ammonia are performedpreferably at 20° C. or at the slightly elevated temperature of 20° to40° C.

The sequence in which the starting compounds are reacted is of decisiveimportance. For the reaction with dicyandiamide alone, the phosphonicacid is placed into the reaction vessel and subsequently reacted withdicyandiamide, whereas for the reaction with guanidine alone, thepreferred procedure is to place guanidine carbonate in the reactionvessel and to then react it with the phosphonic acid. When bothdicyandiamide and guanidine are used, phosphonic acid is placed into thereaction vessel, and reacted firstly with dicyandiamide and lastly withguanidine or preferably with guanidine carbonate. Where the optionalreaction with ammonia is carried out, the ammonia is preferably addedlast if dicyandiamide is used, whilst with use of guanidine, thephosphonic acid is firstly reacted with ammonia and finally withguanidine or preferably with guanidine carbonate.

To produce the phosphonic acid salts of the formula (2), the procedureis to react 1 mol of ethane- or methanephosphonic acid with 2 mols ofdicyandiamide or 1 mol of guanidine carbonate where p and q in theformula (2) have the same meaning, or with 1 mol of dicyandiamide and0.5 mol of guanidine carbonate where p and q in the formula (2) differfrom one another.

The phosphonic acid salts of the formulae (3) and (4) are produced byreacting 1 mol of ethane- or particularly methanephosphonic acid with 1mol of dicyandiamide at 60° to 100° C., and subsequently with 0.5 mol ofguanidine carbonate at 20° to 60° C.; the phosphonic acid salts of theformulae (5) and (6) are produced by reacting 1 mol of guanidinecarbonate with 1 mol of ethane- or preferably methanephosphonic acid at20° to 60° C.; and the phosphonic acid salts of the formulae (7) and (8)are produced by reacting 1 mol of ethane- or preferablymethanephosphonic acid with 2 mols of dicyandiamide at 60° to 100° C.

To produce the phosphonic acid salts of the formula (9), 1 mol ofethane- or methanephosphonic acid is reacted with 1 mol of dicyandiamidewhere p in the formula (9) is 1, or with 0.5 mol of guanidine carbonatewhere p in the formula (9) is 2, and 1 mol of an aqueous ammoniasolution where n in the formula (9) is 1.

The phosphonic acid salts of the formulae (10) and (11) are producedwith the use of guanidine carbonate by an analogous procedure.

To produce the phosphonic acid salt of the formula (12), 1 mol ofmethanephosphonic acid is reacted with 1 mol of an aqueous ammoniasolution and subsequently with 0.5 mol of guanidine carbonate; and toproduce the phosphonic acid salt of the formula (13), 0.5 mol ofguanidine carbonate is reacted with 1 mol of methanephosphonic acid at20° to 60° C.

The phosphonic acid salts of the formulae (14) and (15) are producedusing dicyandiamide with an analogous procedure.

To produce the phosphonic acid salt of the formula (16), 1 mol ofmethanephosphonic acid is reacted with 1 mol of dicyandiamide at 60° to100° C., and subsequently with 1 mol of an aqueous ammonia solution at20° to 60° C.; and to produce the phosphonic acid salt of the formula(17), the procedure is carried out as just described except however thatthe ammonia solution is not used.

The application process according to the invention for fireproofingorganic fibre material, whereby the phosphonic acid salts of the formula(1) are used as fireproofing agents, comprises treating this materialwith an aqueous solution of at least one phosphonic acid salt of theformula (1) and subsequently drying the treated material.

In this process, the treatment of the fibre material is in generalcarried out using the spraying and especially padding methods. Alsosuitable is for example the immersion method, or preferably theslop-padding method.

Since the phosphonic acid salts of the formula (1) are water-soluble,additions of auxiliaries for promoting solubility in the applicationbaths and liquors or spray solutions are as a rule not necessary.Customary softening agents or surface-active agents can however withadvantage be concomitantly used.

In the preferred padding process, the phosphonic acid salt solutions areapplied, with a liquor absorption of for example 60 to 110, preferably60 to 100, particularly 65 to 80, percent by weight, to the fibrematerial to be finished, and the impregnated material is subsequentlydried, as a rule at temperatures of 60° to 200° C., preferably howeverat most at 150° C., for example between 60° and 150° C. and especiallybetween 120° and 150° C.

The process according to the invention is suitable for fireproofingorganic fibre materials, including wood, but preferably paper, and forexample carpets, or particularly textiles in any stage of processing,such as filaments, yarns, spools, fleeces, knitted goods, fabrics orfinished articles of clothing, or furnishing fabrics, such as carpets,furniture coverings, curtains or fabric-covered carpets.

The organic fibre material to be finished can be of natural or syntheticorigin, or can consist of mixtures of natural and synthetic fibres.Suitable natural fibres are especially keratin- or cellulose-containingfibres, including fibres made from regenerated cellulose, such as linen,hemp, sisal or ramie fibres, and preferably wool and cotton fibres,and/or artificial silk, rayon staple or viscose fibres.

Also suitable in addition to pure cellulose fibres are mixtures thereofwith synthetic fibres, the proportion of cellulose being preferably 20to 80 percent by weight of the mixture. Synthetic fibres which can betreated are for example polyesters, preferably acrylonitrile copolymers,and in particular polyacrylonitrile. Applicable also, although lesspreferred, are fibres formed from cellulose acetate, for examplecellulose-21/2-acetate and cellulose triacetate, and fibres made fromcrosslinked polyvinyl alcohols, for example acetates or ketals ofpolyvinyl alcohols.

Of primary interest, besides cellulose fibres and mixtures thereof withsynthetic fibres, are however pure synthetic fibre materials, especiallythose made from polyester or in particular polyacrylonitrile oracrylonitrile copolymers. Polyacrylonitrile carpets can be particularlywell fireproofed according to the invention. Such polyester fibres arederived especially from terephthalic acid, for example frompoly-(ethylene glycol terephthalate) or frompoly-(1,4-cyclohexylenedimethylene terephthalate). In the case of theacrylonitrile copolymers, the proportion of acrylonitrile isadvantageously at least 50, preferably at least 85, percent (by weight)of the copolymer. They are above all copolymers for the producing ofwhich other vinyl compounds, for example vinyl chloride, vinylidenechloride, methyl acrylates, acrylamide or styrenesulfonic acids, havebeen used as comonomers.

The aqueous solutions, with which the said fibre materials are treated,contain as a rule, as the agent for carrying out the application processaccording to the invention, 25 to 500 g of a phosphonic acid salt of theformula (1) per liter, and optionally customary additives, such as thesoftening agents or surface-active agents (tensides) mentioned in theforegoing. Particularly in the treatment of purely synthetic fibrematerials, for example those made from polyester, by use of thepreferred padding method, bath concentrations of 25 to 100 g/l suffice,especially when ammonium salts are present in the bath. Preferably,however, bath concentrations of 200 to 450 g/l are used in the paddingprocess, in particular when a fireproof finish is being imparted topolyacrylonitrile fibres. The pH-value of the solutions used accordingto the invention is generally 3 to 9.

The necessary coating with a compound of the formula (1) for obtainingan adequate fireproofing effect varies depending on the type of fibresand material, and is as a rule between 2 and 40%, relative to the weightof fibres.

Permanent fireproofing effects are not obtained by the process accordingto the invention, so that consequently the treated fibre materialsshould not undergo any subsequent washing treatment. The processaccording to the invention is characterised above all in that the mostvaried types of substrates can be effectively fireproofed by thisprocess.

The fastness to light of dyed or brightened fibre materials is virtuallyunaffected by the coatings according to the invention. Furthermore, thegood compatibility of the phosphonic acid salts, used according to theinvention, with most textile finishing agents, such as with water- andoil-repellent agents or stiffening and softening agents, is especiallyadvantageous. The small deposited amounts necessary for fireproofingpolyester fibres are an additional advantage of the process according tothe invention.

The most significant advantage of the present invention, however, isthat the fibre materials can be dried not only at the usual dryingtemperatures of up to 100° C. but also at higher temperatures, forexample between 100° and 200° C., especially between 120° and 150° C.,without the mechanical properties of the fibre materials dried in thismanner, such as handle, hygroscopicity and tearing strength, becominggreatly impaired. In particular, the fibre materials treated accordingto the invention are less inclined to yellow at high drying temperaturesthan are fibre materials fireproofed by methods hitherto known. Withdrying at elevated temperature, the drying time is all the shorter thehigher the temperature. A drying time of 1/2 to 1 minute is as a rulesufficient at 200° C. whilst at 140° to 160° C. 2 to 10 minutes aregenerally required. The saving in time as a result of the shorteneddrying time enables a higher capacity of the finishing plants to beachieved. This drying at elevated temperature, also denoted as"overdrying" can be carried out in practice using nozzle dryers ofconventional design.

Particularly cellulose-containing fibre materials tend on beingsubjected to overdrying to yellow and to undergo disadvantageous changeswith respect to their textile-mechanical properties. In contrast to thefireproofing agents hitherto used, particularly known phosphonic acidsalts, the phosphonic acid salts according to the invention surprisinglyenable the yellowing and impairment of the textile-mechanicalproperties, even with overdrying of, in particular, cellulose-containingfibre materials, to be largely eliminated.

Accordingly, cellulose fibres can be impregnated in the applicationprocess according to the invention, using the padding method, with anaqueous solution of a phosphonic acid salt of the formula (1), andsubsequently dried at 120° to 150° C.

The values given in the following Examples for "parts" and percentagesrelate to weight.

PRODUCTION EXAMPLES Example 1

986 parts of a 97.4% methanephosphonic acid (10 mols) are dissolved in1800 parts of de-ionised water at 20° C., and the solution is heated to90° C. In the course of 30 minutes, 840 parts of dicyandiamide (10 mols)are added at 90° C. to the methanephosphonic acid solution, the reactionmixture being occasionally cooled. The reaction mixture is subsequentlyheld at 90° C. for 90 minutes and then cooled to 20° C. There are thusobtained 3594 parts of an aqueous, colourless, clear solution having apH-value of 3.0, and a content of phosphonic acid salt of the formula(17) of 48.0% (87.1% of theory) and of unreacted methanephosphonic acidof 4.2% (15.5% of the amount used), the stated contents of salt and acidbeing determined by virtue of titration of a specimen of the reactionsolution with an aqueous sodium hydroxide solution.

A portion of the aqueous solution obtained is concentrated under reducedpressure at a temperature of at most 50° C., and subsequently dried at50° C. under reduced pressure. 200 parts of the dried crude substancethus obtained are freed from the unreacted methanephosphonic acid bybeing washed three times at 20° C. with 200 parts of isopropanol eachtime, and then dried at 50° C. under reduced pressure. The crudesubstance purified in this manner has a melting point of 151° C. and acontent of phosphonic acid salt of the formula (17) of 95.8%. Thispurified crude substance is free from unreacted methanephosphonic acid.

For the purpose of analysis, 10 parts of the resulting crude substanceare recrystallised in 400 parts of 95% ethanol. The recrystallised puresubstance is in the form of white powder and has a melting point of 163°C.

    ______________________________________                                        Elementary analysis of the recrystallised pure substance                      ______________________________________                                        calculated                                                                             C 18.18%  H 5.55%   N 28.29% P 15.65%                                found    C 18.2%   H 5.4%    N 28.3%  P 15.4%                                 ______________________________________                                    

Example 2

46 parts of a 25% aqueous ammonia solution (0.68 mol) is added at 20° C.within 20 minutes, with occasional cooling of the reaction mixture, to207 parts of the aqueous solution obtained in Example 1, which has acontent of 48% of phosphonic acid of the formula (17) (0.5 mol) and of4.2% of free methanephosphonic acid (0.09 mol). The result is 253 partsof a cloudy aqueous solution, which is subsequently filtered. The nowclear solution contains 42% (100% of theory) of phosphonic acid of theformula (16) and 4.6% of methanephosphonic acid diammonium salt.

A part of the aqueous solution obtained is concentrated at a maximum of50° C. under reduced pressure, and then dried at 50° C. under reducedpressure. The crude substance thus obtained melts at 90° to 125° C. withdecomposition (evolution of ammonia), and gives the following elementaryanalysis: calculated: C: 16.75%; H: 6.56%; N: 32.55%; P: 14.40%; found:C: 16.6%; H: 6.4%; N: 29.7%; P: 14.1%.

Example 3

A solution of 124 parts of a 99% guanidine carbonate (0.68 mol) in 2150parts of de-ionised water is added at 50° C. within 30 minutes to 413parts of the aqueous solution obtained in Example 1, which solutioncontains 48% of phosphonic acid of the formula (17) (1 mol) and 4.2% offree methanephosphonic acid (0.18 mol). The reaction mixture is kept atthis temperature for 30 minutes until the evolution of CO₂ has finished,and the reaction mixture is subsequently cooled to 20° C. The yield is2656 parts of a colourless, clear aqueous solution containing 9.68%(100% of theory) of phosphonic acid salt of the formula (4) and 1.45% ofphosphonic acid salt of the formula (6).

A portion of the aqueous solution obtained is concentrated at atemperature of at most 50° C. under reduced pressure, and subsequentlydried at 50° C. under reduced pressure. 10 parts of the crude substancethus obtained are recrystallised in 100 parts of ethanol and 35 parts ofwater. There is obtained as recrystallised substance the phosphoric acidsalt of the formula (4), which melts at 298° to 300° C. withdecomposition and gives the following elementary analysis: calculated:C: 17.44%; H: 6.62%; N: 35.59%; P: 11.24%; found: C: 17.9%; H: 7.1%; N:35.6%; P: 11.2%.

Example 4

A solution of 512.5 parts of a 93.7% methanephosphonic acid (5 mols) in100 parts of de-ionised water is added at 20° C., within 15 minutes, toa solution of 455 parts of a 99% guanidine carbonate (2.5 mols) in 1000parts of de-ionised water, in the course of which the reaction mixturewarms up to 25° C. The reaction mixture is then heated to 50° C.; it isheld at this temperature for 30 minutes, and subsequently concentratedat 50° C. under reduced pressure to obtain 1550 parts of a clear,colourless aqueous solution containing 50% (100% of theory) of thephosphonic acid salt of the formula (13).

A portion of the aqueous solution thus obtained is concentrated at atemperature of at most 50° C. under reduced pressure, and then dried at50° C. under reduced pressure. Ten parts of the crude substance obtainedare recrystallised in 200 parts of absolute ethanol; the recrystallisedsubstance has a melting point of 125° to 129° C. and gives the followingelementary analysis: calculated: C: 15.49%; H: 6.50%; N: 27.09%; P:19.97%; found: C: 15.7%; H: 6.6%; N: 26.9%; P: 19.9%.

Example 5

A solution of 51.25 parts of a 93.7% methanephosphonic acid (0.5 mol) in100 parts of de-ionised water is added at 20° C., within 20 minutes, toa solution of 91 parts of a 99% guanidine carbonate (0.5 mol) in 200parts of de-ionised water, in the course of which the reaction mixturewarms up to 27° C. It is then heated to 50° C.; it is subsequently heldat this temperature for 30 minutes, concentrated at a maximum of 55° C.under reduced pressure, and afterwards dried at 50° C. under reducedpressure. The yield is 106 parts of the phosphonic acid salt of theformula (6) (99% of theory), which is in the form of a white crystallinesubstance, which does not melt until 250° C.

Elementary analysis: calculated: C: 16.83%; H: 7.06%; N: 39.24%; P:14.46%; found: C: 18.8%; H: 6.8%; N: 37.5%; P: 14.7%.

Example 6

34 parts of a 25% aqueous ammonia solution (0.5 mol) are added, within 5minutes, to a solution of 48.35 parts of a 99.3% methanephosphonic acid(0.5 mol) in 200 parts of de-ionised water, in the course of which thetemperature of the reaction mixture rises to 40° C. After completion ofthe addition of ammonia, there is added to the reaction mixture, within5 minutes, a solution of 45.5 parts of a 99% guanidine carbonate (0.25mol) in 200 parts of de-ionised water, during which time the temperatureof the reaction mixture falls to 30° C. The resulting aqueousopal-cloudy solution is concentrated at a maximum of 50° C. underreduced pressure, and subsequently dried at 40° C. under reducedpressure. The yield is 83 parts (96.4% of theory) of the phosphonic acidsalt of the formula (12), which is in the form of a white crystallinesubstance, which melts at 137° C. with decomposition.

Elementary analysis: calculated: C: 13.96%; H: 7.62%; N: 32.54%; P:18.00%; found: C: 14.2%; H: 6.9%; N: 29.3%; P: 18.8%.

Example 7

59.15 parts of a 97.4% methanephosphonic acid (0.6 mol) are dissolved in292 parts of de-ionised water at 20° C., and the solution is heated to90° C. To this methanephosphonic acid solution are then added at 90° C.within 15 minutes, with occasional cooling of the reaction mixture,100.8 parts of dicyandiamide (1.2 mols). The reaction mixture issubsequently held at 97° C. for 15 hours, and then cooled to 20° C.After a water-insoluble by-product formed during the reaction (33 partsof dry substance) has been filtered off, there remain 390 parts of acolourless, clear aqueous solution containing 38% (82.3% of theory) ofthe phosphonic acid salt of the formula (8).

A portion of the aqueous solution obtained is concentrated at atemperature of at most 50° C., and subsequently dried at 50° C. underreduced pressure. The crude substance thus obtained melts from 155° C.,with decomposition, and gives the following elementary analysis:calculated: C: 20.00%; H: 5.71%; N: 37.33%; P: 10.32%; found: C: 18.9%;H: 5.9%; N: 36.6%; P: 10.4%.

Example 8

135.8 parts of a 81% ethanephosphonic acid (1 mol) are dissolved in 150parts of de-ionised water at 20° C., and the solution is heated to 85°C. There are then added to the ethanephosphonic acid at 85° C., within30 minutes, 84 parts of dicyandiamide (1 mol); and after completion ofthe addition, the temperature of the reaction mixture risesautomatically within 10 minutes to 92° C. The reaction mixture issubsequently held at 85°-90° C. for 11/2 hours, and is then cooled to20° C. The yield is 372 parts of an aqueous, clear colourless solution,which is concentrated at 60°-65° C. under reduced pressure. There arethus obtained, as crude substance, 232 parts (100% of theory) of apartially crystallised white product containing 20 parts of water. Thisproduct is recrystallised in 300 parts of 95% ethanol to obtain 79.5parts of the recrystallised pure substance of the formula (14) wherein yand n are 2: this substance is in the form of a crystalline white powderwhich melts at 163° to 164° C., with decomposition, and gives thefollowing elementary analysis: calculated: C: 22.76%; H: 5.73%; N:26.54%; P: 14.67%; found: C: 22.8%; H: 6.0%; N: 26.4%; P: 14.6%.

APPLICATION EXAMPLES Example 9

Various fabrics are padded with an aqueous liquor of the compositiongiven in the following Table I, and then dried at 80° C. for 30 minutes.After drying, a test to determine the fireproofing effect is carried outaccording to DOC FF 3-71 (burning time 3 seconds). An assessment of theeffect the fireproofing finish has on the handle is carried out afterdrying of the respective fabric. Handle is assessed on the basis of ascale of ratings from 0 to 4, the best rating 0 corresponding to theuntreated fabric, and the poorest rating 4 to an undesirable stiffhandle.

All the test results are summarised in the following Table I.

                  TABLE I                                                         ______________________________________                                               Type and weight per unit area of                                              the fabric                                                                                      polyester/                                                          polyacrylo-                                                                             cotton                                                      cotton    nitrile     50:50                                                   (140 g/m.sup.2)                                                                         (138 g/m.sup.2)                                                                           (167 g/m.sup.2)                                               un-             un-         un-                                         treated                                                                             treated treated treated                                                                             treated                                                                             treated                              ______________________________________                                        g of 48% 166     0       702   0     694   0                                  aqueous                                                                       solution                                                                      of the salt                                                                   of the                                                                        formula (17)                                                                  according to                                                                  Example 1                                                                     per liter                                                                     of liquor                                                                     % of coating                                                                           6.6     --      37.0  --    22.1  --                                 of salt                                                                       of the                                                                        formula (17)                                                                  after drying                                                                  fireproofness                                                                 burning time                                                                           3       burns   3     burns 2     burns                              (sec.)                                                                        tear length                                                                            6               3.5         7                                        (cm)                                                                          handle   0.5     0       2     0     2.5   0                                  (ratings)                                                                     ______________________________________                                    

The handle ratings show that the handle of the treated fabric issomewhat fuller than the handle of the untreated fabric.

Example 10

A cotton fabric (weight per unit area 140 g/m²) is padded with anaqueous liquor of the composition given in the following Table II, andis then dried at 150° C. for 5 minutes in a nozzle dryer. After drying,a test is carried out to determine the flameproofing effect in themanner described in Example 9. The tear strength of the fabric issubsequently measured according to SNV 198 461. The values correspond tothe percentage tear strength relative to that of untreated material. Thecolour-difference values are ascertained according to DIN 6174 D 65/10.The higher the value the more severe the degree of yellowing. All theresults are summarised in the following Table II.

                  TABLE II                                                        ______________________________________                                                       Treated   Untreated                                                           cotton fabric                                                                           cotton fabric                                        ______________________________________                                        g of 48% aqueous solution of                                                                   208         0                                                the salt of the formula (17)                                                  according to Example 1                                                        per liter of liquor                                                           pH-value of the liquor                                                                         3.1         --                                               % coating of salt of the                                                                       7.8         0                                                formula (17) after drying                                                     fireproofness                                                                 burning time (sec.)                                                                            2           burns                                            tear length (cm) 8                                                            tear strength %                                                               warp             92          100                                              weft             88          100                                              colour-difference values                                                                       3.5         0                                                ______________________________________                                    

The colour-difference values show that the treated fabric yellows onlyslightly more than the untreated fabric.

Example 11

A cotton fabric (weight per unit area 140 g/m²) is padded with anaqueous liquor of the composition given in the following Table III, andthen dried for 5 minutes at 150° C. After drying, the fireproofingeffect, the tear strength, the colour difference and the handle aretested in the manner described in Examples 9 and 10. The results areshown in the following Table III.

                  TABLE III                                                       ______________________________________                                                       Treated   Untreated                                                           cotton fabric                                                                           cotton fabric                                        ______________________________________                                        g of 9.68% aqueous solution                                                                    1000        0                                                of the salt of the formula                                                    (4) according to Example 3                                                    per liter of liquor                                                           pH-value of the liquor                                                                         6.2         --                                               % coating of salt of the                                                                       7.8         --                                               formula (4) after drying                                                      fireproofness                                                                 burning time (sec.)                                                                            2           burns                                            tear length (cm) 5.5                                                          tear strength %                                                               warp             96          100                                              weft             91          100                                              colour-difference values                                                                       3.8         0                                                handle (ratings) 0.5         0                                                ______________________________________                                    

Similar results are obtained with the salts of any one of the formulae(8), (12) and (16).

Example 12

Various fabrics are padded with an aqueous liquor of the compositiongiven in the following Table IV, and then dried at 80° C. for 30minutes. After drying of the material, the fireproofing effect is testedin the manner described in Example 9. Also measured after drying is thedegree of whiteness according to the CIBA/GEIGY white scale (cp.CIBA/GEIGY Rundschau 1973/1, pp. 23 to 24) (the lower the degree ofwhiteness the more severe the yellowing), and a further valuedetermined, after drying and subsequent two-days' storage of the fabricsat 65% relative humidity, is the hygroscopicity of the treated fabricson the basis of the increase in weight. The hygroscopicity is calculatedas a percentage of the original weight of fabric. The results aresummarised in the following Table IV.

                  TABLE IV                                                        ______________________________________                                                     Type and weight per unit area                                                 of the fabrics                                                                           polyester/                                                         polyacrylo-                                                                              cotton                                                             nitrile    50:50                                                              (138 g/m.sup.2)                                                                          (167 g/m.sup.2)                                                           un-              un-                                                   treated                                                                              treated treated  treated                                  ______________________________________                                        g of salt of the formula                                                                     270      0       300    0                                      (6) according to Example                                                      5 per liter of liquor                                                         pH-value of the liquor                                                                       8.8      --      8.8    --                                     % coating of salt of the                                                                     26.8     --      24.9   --                                     formula (6) after drying                                                      fireproofness                                                                 burning time (sec.)                                                                          2        burns   0      burns                                  tear length (cm)                                                                             8                4                                             degree of whiteness                                                                          -44      15      -33    68                                     hygroscopicity (% water                                                                      1.4      0.9     6.6    7.2                                    absorption)                                                                   ______________________________________                                    

The measured results for the degree of whiteness show that treatedfabric yellows only slightly more than untreated fabric.

Similar results are obtained with the salts of any one of the formulae(4), (8), (12) and (16).

Example 13

A cotton fabric (weight per unit area 140 g/m²) is padded with anaqueous liquor of the composition given in the following Table V, and issubsequently dried at 150° C. for 5 minutes. After drying of the treatedmaterial, tests are carried out to determine the fireproofing effect,the tear strength, the degree of whiteness and the hygroscopicity in themanner indicated in Examples 9, 10 and 12. The results are summarised inthe following Table V.

                  TABLE V                                                         ______________________________________                                                       Treated    Untreated                                                          cotton fabric                                                                            cotton fabric                                       ______________________________________                                        g of salt of the formula (6)                                                                   105      135     0                                           according to Example 5                                                        per liter of liquor                                                           pH-value of the liquor                                                                         8.9      8.9     --                                          % coating of salt of the                                                                       6.6      9.7     --                                          formula (6) after drying                                                      fireproofness                                                                 burning time (sec.)                                                                            1        2       burns                                       tear length (cm) 7        6                                                   tear strength %                                                               warp             105      98      100                                         weft             92       97      100                                         degree of whiteness                                                                            -9       -25     67                                          hygroscopicity (% absorption                                                                   6.8      6.8     7.4                                         of water)                                                                     ______________________________________                                    

Example 14

A polyacrylonitrile fabric (weight per unit area 138 g/m²) is paddedwith an aqueous liquor of the composition shown in the following TableVI, and is then dried at 80° C. for 30 minutes. After drying of thematerial, the fireproofing effect is tested as given in Example 9. Theresults are summarised in the following Table VI.

                  TABLE VI                                                        ______________________________________                                                         Treated Untreated                                                             polyacrylo-                                                                           polyacrylo-                                                           nitrile nitrile                                                               fabric  fabric                                               ______________________________________                                        g of 50% aqueous solution                                                                        500       0                                                of the salt of the formula                                                    (13) according to Example 4                                                   per liter of liquor                                                           fireproofness                                                                 burning time (sec.)                                                                               3        burns                                            tear length (cm)    4                                                         ______________________________________                                    

Example 15

A cotton fabric (weight per unit area 140 g/m²) is padded with anaqueous liquor of the composition shown in the following Table VII, andis then dried at 150° C. for 5 minutes. After drying of the material,the test to determine the fireproofing effect and the tear strength iscarried out as given in Examples 9 and 10. The results are summarised inthe Table VII which follows.

                  TABLE VII                                                       ______________________________________                                                       Treated   Untreated                                                           cotton fabric                                                                           cotton fabric                                        ______________________________________                                        g of 50% aqueous solution                                                                      250          0                                               of the salt of the formula                                                    (13) according to Example 4                                                   per liter of liquor                                                           fireproofness                                                                 burning time (sec.)                                                                            1           burns                                            tear length (cm) 2.5                                                          tear strength %                                                               warp             93          100                                              weft             88          100                                              ______________________________________                                    

Example 16

A polyester/cotton mixed fabric 50:50 (weight per unit area 167 g/m²) ispadded with an aqueous liquor of the composition shown in the followingTable VIII, and is then dried at 150° C. for 5 minutes in a nozzledryer. After drying of the material, the fireproofing effect is testedas given in Example 9, and the tear strength and colour differencevalues as given in Example 10. The results are summarised in the TableVIII which follows.

                  TABLE VIII                                                      ______________________________________                                                     Treated  Untreated                                                            polyester/                                                                             polyester/                                                           cotton   cotton                                                               mixed fabric                                                                           mixed fabric                                            ______________________________________                                        g of salt of the                                                                             300         0                                                  formula (7) wherein                                                           y is 2, according to                                                          Example 8, per liter                                                          of liquor                                                                     pH-value of the                                                                              3.9        --                                                  liquor                                                                        % coating of salt                                                                            20.2       --                                                  of the formula (7)                                                            wherein y is 2                                                                after drying                                                                  fireproofness                                                                 burning time (sec)                                                                           16         burns                                               tear length (cm)                                                                             5                                                              tear strength %                                                               warp           95.7       100                                                 weft           77.4       100                                                 colour-difference                                                                            2.4         0                                                  values                                                                        ______________________________________                                    

What is claimed is:
 1. A phosphonic acid salt of the formula ##STR22##in which n, q, t and y are each 1 or
 2. 2. A phosphonic acid salt ofclaim 1 wherein t is
 2. 3. A phosphonic acid salt of claim 2 wherein yis
 1. 4. A phosphonic acid salt of claim 1 wherein t is
 1. 5. Aphosphonic acid salt of claim 4 wherein y is
 1. 6. A process forfireproofing organic fibers, comprising the step of applying to thefibers an aqueous solution of a phosphonic acid salt of claim
 1. 7. Theprocess of claim 6, wherein the aqueous solution is applied to thefibers by padding and subsequent drying at 60° to 200° C.
 8. The processof claim 6, wherein the aqueous solution contains 25 to 500 g/l of saidphosphonic acid salt.
 9. The process of claim 6, wherein the fiberscontain cellulose, synthetic polymer or mixtures thereof.
 10. Theprocess of claim 6, wherein the fibers are polyacrylonitrile, polyester,cellulose or polyester/cellulose.
 11. An aqueous solution of aphosphonic acid salt of claim
 1. 12. Organic fibers bearing thereon afire retardant finish conferred by the process of claim 6.